Bash/perl script to determine network activity

mrjoe42 · 07-07-2009, 05:56 PM

I was wondering if anyone had a small script (preferably bash, but will work with perl) that I could use to determine if there's a certain amount of network activity.

Currently closing the lid on my laptop doesn't do anything. If I want to put it to sleep I have to use a fn-key press. I'd like to configure it to sleep when the lid is closed (and I know how), but if I'm in the middle of a download I'd prefer it to not do anything but turn the screen off.

I don't mind working out a level of network activity to trigger on and I'm familiar enough with bash/perl to start, just need some ideas on the best way to do this.

Robhogg · 07-07-2009, 07:03 PM

I don't have anything written, but I've been poking around and found that the file /proc/net/dev contains a line for each interface, which contains, inter-alia, the number of bytes received and sent. This might be a starting point:

Code:

net_stats () {
iface=$(grep 'eth0:' /proc/net/dev) # assuming your connection is via eth0
iface=${iface#*:} # strip the eth0: prefix
rec=$(echo $iface | awk '{print $1}') # field 1 contains the bytes received
tran=$(echo $iface | awk '{print $9}') # field 9 contains the bytes sent
}

traffic_per_sec () {
net_stats
last_rec=$rec
last_tran=$tran
sleep 1
net_stats
traffic=$((($rec - $last_rec) + ($tran - $last_tran)))
}

You'd probably want a few zero readings (or a zero reading over a longer interval than 1 second) before deciding that a download has finished, rather than just paused for a while, though.